"The publication today by Wikileaks of thousands of highly-classified documents about the war in Afghanistan is deeply troubling and a serious breach of national security," McCain said in a statement Monday.
McCain, the ranking member of the Senate Armed Services Committee and a former Vietnam POW, said he doesn't buy the claim of Wikileaks founder, Australian Julian Assange, that the organization is politically neutral.
"Wikileaks has a clear agenda, and it is not to win the war in Afghanistan" McCain said. "This biased organization seeks to undermine the achievement of a vital national security interest that more than one thousand Americans have already given their lives to safeguard. This is the height of irresponsibility, and all involved should be ashamed of themselves," said McCain.
Wikileaks on Sunday published more than 90,000 documents containing classified information about the Afghan conflict. Interest in the postings quickly spread globally, and Wikileaks' site appeared to be offline early Monday under the strain of all the traffic, but was up and running Tuesday.
The documents cover developments in the war from 2004 to 2009, and purport to show that the conflict's true course is at odds with statements from the White House and U.S. military commanders.
For instance, Wikileaks claims the files reveal that secret service operators from Pakistan, supposedly a U.S. ally, have been working with Afghan insurgents to sabotage the Western coalition's military and political efforts in the region.
Wikileaks posted the documents directly to its site, and also leaked them in advance to The New York Times, The Guardian, and Germany's Der Spiegel, all of which ran major stories based on the material on Sunday. Wikileaks has not identified the source of the documents.
In addition to McCain, many other U.S. officials blasted Wikileaks for making the material available. "The United States strongly condemns the disclosure of classified information by individuals which could put the lives of Americans and our partners at risk, and threaten our national security," said National Security Adviser James Jones, in a statement.
"These irresponsible leaks will not impact our ongoing commitment to deepen our partnerships with Afghanistan and Pakistan; to defeat our common enemies; and to support the aspirations of the Afghan and Pakistan people," said Jones.
Wikileaks has drawn criticism from the military in the past for posting documents and videos related to the Afghan and Iraq conflicts that officials said lacked context and were therefore misleading to the public.